1. Field of the Invention
The present invention relates to a method of cleaning a substrate processing chamber, a storage medium, and a substrate processing chamber, and in particular relates to a method of cleaning a substrate processing chamber having an electrode made of silicon.
2. Description of the Related Art
Plasma processing apparatuses having a substrate processing chamber having therein a processing space into which is transferred a semiconductor wafer as a substrate, and a lower electrode that is disposed in the processing space and is connected to a radio frequency power source are known. In such a plasma processing apparatus, a processing gas is introduced into the processing space, and the lower electrode applies radio frequency electrical power into the processing space. Moreover, when a semiconductor wafer has been transferred into the processing space and mounted on the lower electrode, the introduced processing gas is turned into plasma by the radio frequency electrical power, whereby ions and so on are produced, and the semiconductor wafer is subjected to plasma processing such as etching through the ions and so on.
In such a plasma processing apparatus, in the case that a mixed gas of a deposit-producing reactant gas such as C4F8 gas and argon (Ar) gas is used as the processing gas, reaction product produced from the reactant gas becomes attached to an inner surface, e.g. a side inner wall (hereinafter referred to merely as the “side wall”), of the substrate processing chamber. The attached reaction product may peel away from the side wall, becoming particles. Such particles may become attached to a semiconductor wafer, causing defects in semiconductor devices manufactured from the semiconductor wafer. If it thus necessary to remove the reaction product attached to the inner surface of the substrate processing chamber.
From hitherto, as a method of removing reaction product attached to the inner surface, there has been known a method in which oxygen (O2) gas is introduced into the processing space, oxygen ions and oxygen radicals are produced from the oxygen gas by radio frequency electrical power, and the reaction product is removed through reaction with the oxygen ions and oxygen radicals (see, for example, Japanese Laid-open Patent Publication (Kokai) No. S62-040728).
In recent years, with an object of improving plasma processing performance, there have been developed plasma processing apparatuses in which an upper electrode as a processing chamber inside component disposed facing the lower electrode in the processing space is made of silicon, and a DC power source is connected to the upper electrode. In such a plasma processing apparatus, if the reaction product removal method described above is implemented, then reaction product attached to the inner surface of the substrate processing chamber is reliably removed, but oxide such as silicon oxide (SiO2) is produced through reaction of the silicon of the upper electrode with the oxygen ions and oxygen radicals. The oxide may become attached to the surface of the upper electrode so as to form an oxide film. The oxide film may peel away, becoming particles. Moreover, direct current cannot pass through the oxide film, and hence applying a DC voltage into the processing space becomes difficult. Furthermore, the oxide film may undergo dielectric breakdown through such a direct current, and hence making the state of the plasma in the processing space stable is difficult.